Linux Firewall NAT Port Forwarding Issues

Question

At my home I have a Linux server (it's only job is NAT, DHCP, and DNS) with Ubuntu 10.10 Server 64-bit.

I have webmin installed on the server too, but I do know my way around a command line quite well, so I can do anything suggested. I have a game server in my NAT, which hosts on port 28000 UDP, and it's IP address is 10.40.2.25 (Internal).

I setup the port forwarding under Webmin as I do not understand how to use iptables via command line.

When someone attempts to connect to the game server via the Internet, they cannot connect. I took a look at wireshark on the external computer and I see ICMP packets that it needs to connect to the game server (10.40.2.25). The entry says "Destination Unreachable (Port Unreachable)"

I took a look at the packet and noticed it says:

User Datagram Protocol, Src Port: nxlmd (28000), Dst Port: 45282 (45282)

The destination port occasionally changes after a different person connects, so I cannot just forward the port.

Bottom line, is there any way I can have it so packets that should go to my internal game server (10.40.2.25), do go to my internal game server?

Thank you very much in advance!

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Any ideas? Really need to get this working.

Answer 1

This is why router centric distributions were created. They are easy to install and manage without the learning curve of linux networking. If this is the machines only job, I recommend IPCOP or better yet PFSENSE as a replacement. And you will get much more out of those distros than you would ubuntu if you don't know linux-networking and services.